The present invention relates to methods for reducing airport turnaround times, and more particularly relates to reducing safety margins around aircraft moving on taxiways by eliminating the use of aircraft thrust equipment, such as turbines on the ground and motorized tugs to tow aircraft.
It is standard practice at airports that ground personnel who are close to the aircraft when the turbines are running protect their ears from the noise caused by the turbines using protective earphones, and communicate with each other using hand signals since hearing is not possible. Headsets are required to communicate with pilots, in which background noise from turbines causes further communications problems.
FR 2628590 to Hodys discloses a device intended to carry out sound captures without the useful signal being cluttered with ambient noise, and teaches that the device is particularly intended to allow sound captures in a very noisy environment such as for example communications between airport runway staff.
It is further standard safety practise at airports that ground personnel do not approach the aircraft or bring loading bridges, stairs, luggage carts, conveyor belts, or other equipment necessary for unloading passengers and luggage or cargo, to the aircraft until the aircraft turbines have been turned off and come to rest. Only when the precise parked location of the aircraft is known can loading bridges, stairs, luggage carts, etc. be positioned. This causes delays to turnaround times.
The background section of US2004090348 to Hutton discloses some of the delays associated with loading bridges, for example.
JP2002321699 to FUKUHARA and TAKASU discusses some of the issues associated with cargo and luggage loading and unloading. It discloses a tow vehicle that can tow cargo laden equipment such as container dollies and pallet dollies from the cargo holding area inside of the airport terminal building to aircraft parked on the tarmac to thereby automatically transport the air cargo.
In the above prior art dealing with loading and unloading of equipment from aircraft, it is assumed that either the aircraft will taxi to a parking space using its turbines, in which case no processes can take place until the turbines have been turned off and come to a standstill, or that a motorised tug is used to bring the aircraft to a parking space, in which case additional time is required to attach the tug. Here also, ground personnel cannot approach the aircraft to attach the tug until the turbines have been turned off and come to a standstill.
U.S. Pat. No. 5,078,340 to Anderberg and WO03078250 to Mallet disclose methods of automatically moving aircraft along taxiways and into parking spaces using equipment fixed beneath the ground of the taxiways. This enables the turbines to be turned off before parking, but requires extensive alterations to airport taxiways. Furthermore, the equipment may not fit all present or future aircraft.
US2005247824 to Allison discloses an aircraft having a removable passenger compartment and a removable luggage compartment to speed loading and unloading of passengers and luggage. Passengers and luggage are loaded into said removable compartments in advance of the aircraft arriving at the airport. When the aircraft arrives, the removable compartments containing the arriving passengers and luggage are removed and the removable compartments containing the departing passengers and luggage are attached to the aircraft. The aircraft can then take off, while passengers and luggage are still being unloaded from the arriving removable compartments.
Allison thus solves the problem reducing of loading and unloading times for aircraft but at the great expense of totally renewing or vastly modifying fleets of aircraft.
It can be seen from the above that it would be advantageous to enable loading and unloading equipment to approach an aircraft as soon as possible after an aircraft lands, without a major modification to the aircraft or taxiways.
Motors providing high torque at low speeds are known in the art. Specifically, such motors are known that are designed for the purpose of propelling aircraft on the ground.
In WO05/112584 Edelson discloses a motor-generator machine comprising a slotless AC induction motor. The motor disclosed therein is an AC induction machine comprising an external electrical member attached to a supporting frame and an internal electrical member attached to a supporting core; one or both supports are slotless, and the electrical member attached thereto comprises a number of surface mounted conductor bars separated from one another by suitable insulation. An airgap features between the magnetic portions of core and frame. Electrical members perform the usual functions of rotor and stator but are not limited in position by the present invention to either rôle. The stator comprises at least three different electrical phases supplied with electrical power by an inverter. The rotor has a standard winding configuration, and the rotor support permits axial rotation.
In WO05/112584 Edelson discloses a motor-generator machine comprising a high phase order AC machine with short pitch winding. Disclosed therein is a high phase order alternating current rotating machine having an inverter drive that provides more than three phases of drive waveform of harmonic order H, and characterized in that the windings of the machine have a pitch of less than 180 rotational degrees. Preferably the windings are connected together in a mesh, star or delta connection. The disclosure is further directed to selection of a winding pitch that yields a different chording factor for different harmonics. The aim is to select a chording factor that is optimal for the desired harmonics.
In WO2006/065988 Edelson discloses a motor-generator machine comprising stator coils wound around the inside and outside of a stator, that is, toroidally wound. The machine may be used with a dual rotor combination, so that both the inside and outside of the stator may be active. Even order drive harmonics may be used, if the pitch factor for the windings permits them. In a preferred embodiment, each of the coils is driven by a unique, dedicated drive phase. However, if a number of coils have the same phase angle as one another, and are positioned on the stator in different poles, these may alternatively be connected together to be driven by the same drive phase. In a preferred embodiment, the coils are connected to be able to operate with 2 poles, or four poles, under H=1 where H is the harmonic order of the drive waveform. The coils may be connected together in series, parallel, or anti-parallel.
In 2006/0273686, a motor-generator machine is disclosed comprising a polyphase electric motor which is preferably connected to drive systems via mesh connections to provide variable V/Hz ratios. The motor-generator machine disclosed therein comprises an axle; a hub rotatably mounted on said axle; an electrical induction motor comprising a rotor and a stator; and an inverter electrically connected to said stator; wherein one of said rotor or stator is attached to said hub and the other of said rotor or stator is attached to said axle. Such a machine may be located inside a vehicle drive wheel, and allows a drive motor to provide the necessary torque with reasonable system mass.
In WO2006/113121, a motor-generator machine comprising an induction and switched reluctance motor designed to operate as a reluctance machine at low speeds and an inductance machine at high speeds is disclosed. The motor drive provides more than three different phases and is capable of synthesizing different harmonics. As an example, the motor may be wound with seven different phases, and the drive may be capable of supplying fundamental, third and fifth harmonic. The stator windings are preferably connected with a mesh connection. The system is particularly suitable for a high phase order induction machine drive systems of the type disclosed in U.S. Pat. Nos. 6,657,334 and 6,831,430. The rotor, in combination with the stator, is designed with a particular structure that reacts to a magnetic field configuration generated by one drive waveform harmonic. The reaction to this harmonic by the rotor structure produces a reluctance torque that rotates the rotor. For a different harmonic drive waveform, a different magnetic field configuration is produced, for which the rotor structure defines that substantially negligible reluctance torque is produced. However, this magnetic field configuration induces substantial rotor currents in the rotor windings, and the currents produce induction based torque to rotate the rotor.
U.S. Pat. No. 7,226,018 and U.S. Pat. No. 7,237,748 to Delos Aerospace an aircraft landing gear comprised of a wheel hub motor/generator disks stack, including alternating rotor and stator disks mounted with respect to the wheel support and wheel is disclosed. The invention can provide motive force to the wheel when electrical power is applied, e.g. prior to touch-down. After touchdown the wheel hub motor/generator may be used as a generator thus applying a regenerative braking force and/or a motorized braking action to the wheel. The energy generated upon landing maybe dissipated through a resistor and/or stored for later use in providing a source for motive power to the aircraft wheels for taxiing and ground maneuvers of the aircraft.
In US2006/0065779 a powered nose aircraft wheel system for an aircraft which includes landing gear that extends from the aircraft. A wheel axel is coupled to the landing gear is disclosed. A wheel is coupled to the wheel axel. A wheel motor is coupled to the wheel axel and the wheel. A controller is coupled to the wheel motor and rotates the wheel. A method of taxiing an aircraft includes permitting the wheel of the aircraft to freely spin during the landing of the aircraft. Power is transferred from an auxiliary power unit of the aircraft to the wheel motor. The wheel is rotated via the wheel motor. The aircraft is steered and the speed of the wheel is controlled via one or more controllers selected from an onboard controller and an offboard controller.